TECHNICAL FIELD
[0001] This document relates generally to hearing assistance systems and more particularly
to a hearing assistance device that includes an antenna configured for decreasing
degradation in performance of wireless communication due to head loading when the
hearing assistance device is worn.
BACKGROUND
[0002] Hearing assistance devices such as hearing aids are used to assist patients suffering
hearing loss by transmitting amplified sounds to ear canals. The sounds may be detected
from a patient's environment using the microphone in a hearing aid and/or received
from a streaming device via a wireless link. Wireless communication may also be performed
for programming the hearing aid and receiving information from the hearing aid. In
one example, a hearing aid is worn in and/or around a patient's ear. Patients generally
prefer that their hearing aids are minimally visible or invisible, do not interfere
with their daily activities, and easy to maintain. The hearing aids may each include
an antenna for the wireless communication. Due to the loading effect of the patient's
body on the antenna, there is a need for optimizing performance of the wireless communication
without increasing size and/or complexity of a hearing aid.
SUMMARY
[0003] A hearing assistance device such as a hearing aid includes an antenna for wireless
communication with another device. The antenna includes two antenna elements and a
cross-feed that provides for electrical connection between the two antenna elements.
The cross-feed having a flared structure configured to reduce an effect of head loading
on the performance of the wireless communication by approximately minimizing capacitive
coupling between the cross-feed and a wearer when the hearing assistance device is
worn by the wearer.
[0004] This Summary is an overview of some of the teachings of the present application and
not intended to be an exclusive or exhaustive treatment of the present subject matter.
Further details about the present subject matter are found in the detailed description
and appended claims. The scope of the present invention is defined by the appended
claims and their legal equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005]
FIG. 1 is an illustration of an embodiment of a hearing aid including an antenna for
wireless communication.
FIG. 2 is an illustration of an embodiment of the antenna showing its position relative
to the head of the wearer of the hearing aid.
FIG. 3 is an illustration of an embodiment of portions of a hearing aid circuit including
the antenna.
FIG. 4 is an illustration of an embodiment of a cross-feed of the antenna connected
to a feed.
FIG. 5 is an illustration of an embodiment of a flared cross-feed of the antenna.
FIG. 6 is an illustration of an embodiment of portions of a hearing aid circuit including
the antenna with the flared cross-feed.
DETAILED DESCRIPTION
[0006] The following detailed description of the present subject matter refers to subject
matter in the accompanying drawings which show, by way of illustration, specific aspects
and embodiments in which the present subject matter may be practiced. These embodiments
are described in sufficient detail to enable those skilled in the art to practice
the present subject matter. References to "an", "one", or "various" embodiments in
this disclosure are not necessarily to the same embodiment, and such references contemplate
more than one embodiment. The following detailed description is demonstrative and
not to be taken in a limiting sense. The scope of the present subject matter is defined
by the appended claims, along with the full scope of legal equivalents to which such
claims are entitled.
[0007] This document discusses a hearing assistance device, such as a hearing aid, with
an antenna that is configured to reduce effects of "head loading" on performance of
wireless communication. An antenna when placed next to the head of the wearer of the
hearing assistance device (or any other dielectric object) will experience a shift
in impedance. If this shift in impedance is too large for the antenna matching network
of the hearing assistance device to account for at a certain frequency, the wireless
communication at that frequency will either operate with degraded performance or become
inoperable. Examples of solutions to this problem include adding more capacitor banks
to make the matching network tunable and increasing spacing between the antenna and
the wearer. However, such solutions increase the complexity, power consumption, size,
and/or visibility of the hearing assistance device, none of which is desirable, especially
when the hearing assistance device is a hearing aid.
[0008] The present subject matter provides an antenna configured for use in a hearing assistance
device such as a hearing aid with reduced head loading, i.e., reduced shift in impedance
when the hearing aid is placed on the wearer's head (e.g., in and/or around an ear).
In various embodiments, the present subject matter can be implemented with limited
modification of existing antenna configurations and limited or no modification of
other parts of the hearing assistance device. While a loop antenna, particularly a
"butterfly antenna" configuration for used in a behind-the-ear (BTE) type hearing
aid is discussed as a specific example with reference to FIGS. 1-6, the approach to
decreasing coupling between the antenna and the wearer's head as discussed in this
document can be applied to other configurations of antenna used in other types of
hearing assistance devices, including other types of hearing aids, without departing
from the scope of the present subject matter.
[0009] FIG. 1 is an illustration of an embodiment of a hearing aid 100 including an antenna
110 for wireless communication between hearing aid 100 and another device. In the
illustrated embodiment, hearing aid 100 is a behind-the-ear (BTE) type hearing aid,
and antenna 110 is a parallel-loop type antenna housed in a case 116 of hearing aid
100. While the BTE type hearing aid and the parallel-loop type antenna are illustrated
as an example, the present subject matter is applicable to any type hearing aid or
other hearing assistance device with an antenna of any type that may be affected by
head loading when being worn by a person. Examples of antenna 110 include those discussed
in
U.S. Patent Application No. 12/638,720, entitled "PARALLEL ANTENNAS FOR STANDARD FIT HEARING ASSISTANCE DEVICES", filed
on December 15, 2009, published as
US 2010/0158293,
U.S. Patent Application No. 12/340,604, entitled "ANTENNAS FOR STANDARD FIT HEARING ASSISTANCE DEVICES", filed on December
15, 2008, published as
US 2010/0158291,
U.S. Patent Application No. 12/340,600, entitled "ANTENNAS FOR CUSTOM FIT HEARING ASSISTANCE DEVICES", filed on December
19, 2008, published as
US 2010/0158295, and
U.S. Patent No. 7,593,538, entitled "ANTENNAS FOR HEARING AIDS", all assigned to Starkey Laboratories, Inc.,
which are incorporated herein by reference in their entirety.
[0010] Antenna 110 includes two antenna elements 112 and a cross-feed 114 that electrically
connects antenna elements 112. In the illustrated embodiment, antenna elements 112
include two approximately symmetric antenna loops positioned in parallel on opposite
sides of hearing aid 100. The two antenna loops comprise two small (relative to a
wavelength of the operating frequency of the wireless communication) inductive loop
antennas connected in parallel. This antenna inductance is then brought to parallel
resonance by adding a resonating capacitor near the feed-point (where the two antenna
loops are connected with the cross-feed). Cross-feed 114 includes two cross-feed lines
each connected between the two antenna loops. In various embodiments, cross-feed 114
is configured to reduce or approximately minimize its capacitive coupling to the wearer,
particularly the wearer's head and/or ear, when hearing aid 100 is being worn by the
wearer.
[0011] FIG. 2 is an illustration of an embodiment of an antenna 210 showing its position
relative to a head 201 and an ear 202 of a hearing aid wearer when the hearing aid
including antenna 210 is worn. Antenna 210 represents an embodiment of antenna 110
and has a configuration of a "butterfly antenna" as a specific example. FIG. 2 illustrates,
as a specific example, the position of antenna 210 as a parallel-loop type antenna
of a BTE type hearing aid when the hearing aid is worn by the hearing aid wearer.
[0012] When hearing aid 100 is worn by the wearer, and antenna 110 is positioned on the
wearer's head/ear in a way similar to antenna 210 placed on head 201/ear 202 as illustrated
in FIG. 2, the antenna conductors (conductors of antenna loops 112) near cross-feed
114 and cross-feed 114 itself are very sensitive to capacitive loading changes, when
being compared to the portion of antenna 110 opposite the feed-point/cross-feed that
is much less sensitive to the capacitive loading changes. Placing antenna 110 on the
wearer's head causes a substantial shift in the tuning of the antenna's resonant frequency
(i.e., the capacitive loading change) due to coupling between the human head/ear and
the cross-feed/feed-point area of the antenna. In one example, a variable capacitor
implemented near the feed-point automatically retunes the resonating capacitance value
to maintain resonance at the frequency of operation. For this type of hearing aid
design, this tuning shift when placing on the head is problematic in that it takes
a significant portion of the tuning capacitance (over a third of the range), when
most of the range is needed for operating frequency changes and compensating for production
component variations. Additionally, increased coupling to the lossy human head/ear
in this sensitive area of the antenna may also reduce gain/radiation efficiency when
worn on the human head/ear.
[0013] The present subject matter reduces the amount of shift in the tuning of the antenna's
resonant frequency by decreasing coupling of the loop antennas cross-feed/feed-point
area to the wearer's head/ear. FIG. 3 is an illustration of an embodiment of portions
of a hearing aid circuit 320 including an antenna 310. Hearing aid circuit 320 represents
an embodiment of a circuit of hearing aid 100 that is also housed in case 116. In
various embodiments, hearing aid circuit 320 includes a microphone to receive an input
sound, a processing circuit to produce an output signal by processing a signal received
from the microphone, a receiver to produce an output sound using the output signal
and transmits the output sounds to the ear canal of the wearer, and a communication
circuit coupled to antenna 310 to perform wireless communication. Antenna 310 represents
an embodiment of antenna 110 and has a configuration of the "butterfly antenna" (of
the parallel-loop type) as a specific example. Antenna 310 as illustrated in FIG.
3 includes a conductor trace (such as copper trace) forming two antenna loops 312
and a cross-feed 314 coupled between antenna loops 312. In one embodiment, antenna
310 is a flex circuit antenna including the conductor trace on a flex circuit substrate.
An example of such a flex circuit antenna is discussed in
U.S. Patent Application No. 12/638,720, entitled "PARALLEL ANTENNAS FOR STANDARD FIT HEARING ASSISTANCE DEVICES", filed
on December 15, 2009, published as
US 2010/0158293, assigned to Starkey Laboratories, Inc., which is incorporated herein by reference
in its entirety. A feed 322 electrically connects cross-feed 314 (and hence antenna
310) to hearing aid circuit 320. FIG. 4 is an illustration of an embodiment of cross-feed
314 and feed 322 in a zoomed view. Cross-feed 314 represents an embodiment of cross-feed
114, In the illustrated embodiment, cross-feed 314 includes two cross-feed lines each
connected between antenna loops 312, and feed 322 includes two feed lines each connected
to a cross-feed line of cross-feed 314.
[0014] In some examples, portions of antenna 310 including cross-feed 314 and structures
near cross-feed 314 that are normal to the wearer's head when the hearing aid is worn
are limited to reduce the amount of shift in the tuning of the antenna's resonant
frequency. That portion of the antenna is believed to be attributed to higher ear-to-ear
communication performance due to the excitation of the mode across the head that is
most easily excited through normal current distribution to the conductive surface
of the wearer's head and skin. In various embodiments, the present subject matter
flares the cross-feed before the feed point (where the two conductor trace are at
closest distance from each other as illustrated) so that there is less coupling between
cross-feed lines and less area for capacitive loading from the head and specifically
the top of the ear of the wearer. In various embodiments, this requires small modifications
to hearing aid antennas currently distributed in devices in the field, such as those
similar to antenna 310. Such a small modification can significantly improve the performance
of the wireless communication when head loading is a concern.
[0015] FIG. 5 is an illustration of an embodiment of a flared cross-feed 514 of an antenna
510. Antenna 510 represents an embodiment of antenna 110 and includes two antenna
loops 512 and a cross-feed 514 that that electrically connects antenna loops 512.
Antenna loops 512 represent an embodiment of antenna elements 112. Cross-feed 514
represents an embodiment of cross-feed 114 with its structure configured to reduce
the amount of shift in the tuning of the resonant frequency of antenna 110 by decreasing
coupling of the cross-feed/feed-point area of antenna 110 to the wearer's head/ear.
In the illustrated embodiment, in which cross-feed 514 includes two cross-feed lines
each coupled between antenna loops 512 and approximately perpendicular to each loop
of antenna loops 512, this is accomplished by effectively mitering the corners of
the approximately 90-degree bend in the structure of the cross-feed such as illustrated
as cross-feed 314 in antenna 310 and a portion of antenna loop 312 to decrease capacitive
coupling to the wearer's head/ear, by converting the approximately 90-degree bends
(or turns) into two approximately 45-degree bends (or turns). This results in antenna
510 with a flared cross-feed 514. Antenna 510 has been shown to significantly reduce
the shift in the tuning of the antenna's resonant frequency due to coupling between
the wearer's head/ear and the cross-feed/feed-point area of the antenna. Additionally,
it has been shown that reducing coupling from the cross-feed/feed-point area of antenna
514 to the "lossy" human head/ear also yields gain/efficiency improvement for the
antenna when worn on the wearer's head/ear, for example when compared to antenna 314.
[0016] The approximately 90-degree bends and 45-degree bends are illustrated as specific
examples rather than limitations of the present subject matter. In various embodiments,
cross-feed 514 has a flared structure configured to approximately minimize capacitive
coupling between cross-feed 514 and the wearer (primarily the head and/or the ear
of the wearer). The flared structure includes cross-feed lines each having one or
more bends. In various embodiments, the flared structure may include cross-feed 514
and portions of antenna loops 512. In the illustrated embodiment, the flared structure
includes two lines (the two cross-feed lines and portions of the two antenna loops)
each having two approximately 45-degree bends. In various embodiments, the flared
structure includes two lines each include a plurality of bends with angles having
a sum of approximately 90 degrees.
[0017] For hearing aids using antenna 314 or an antenna similar to antenna 314, switching
to antenna 514 has little or no impact on the mechanical foot print of the antenna.
This represents an improvement that increases the antenna efficiency while decreasing
the amount of capacitive loading seen by the antenna from the wearer's body when the
hearing assistance device such as the hearing aid is worn. FIG. 6 is an illustration
of an embodiment of portions of a hearing aid circuit 520 including antenna 510 with
the flared cross-feed 514. Hearing aid circuit 520 represents an embodiment of hearing
aid circuit 320 with antenna 310 replaced by antenna 510.
[0018] While illustrated in FIGS. 1-6 with an antenna in a BTE type hearing aid as a specific
example, the present subject matter is applicable for any antennas that may interfere
with human body or other object in their use and are therefore subject to various
loading effects. The present subject matter is also applicable for any antenna types
including, but not limited to dipoles, monopoles, patches, and combinations of such
types. The application of the present subject matter eliminates the use of certain
hearing aid circuit components such as a tuning circuit that can be adjusted for individual
wearers and/or environments, and prevents the hearing aid from failing to be tuned
for one or more necessary operating frequencies for its wireless communication. In
various embodiments, the present subject matter facilitates miniaturization of wireless
hearing aids and improves antenna performance by reducing deteriorating effects of
human body loading.
[0019] Hearing assistance devices typically include at least one enclosure or housing, a
microphone, hearing assistance device electronics including processing electronics,
and a speaker or "receiver." Hearing assistance devices may include a power source,
such as a battery. In various embodiments, the battery may be rechargeable. In various
embodiments multiple energy sources may be employed. It is understood that in various
embodiments the microphone is optional. It is understood that in various embodiments
the receiver is optional. It is understood that variations in communications protocols,
antenna configurations, and combinations of components may be employed without departing
from the scope of the present subject matter. Antenna configurations may vary and
may be included within an enclosure for the electronics or be external to an enclosure
for the electronics. Thus, the examples set forth herein are intended to be demonstrative
and not a limiting or exhaustive depiction of variations.
[0020] It is understood that digital hearing aids include a processor. In digital hearing
aids with a processor, programmable gains may be employed to adjust the hearing aid
output to a wearer's particular hearing impairment. The processor may be a digital
signal processor (DSP), microprocessor, microcontroller, other digital logic, or combinations
thereof. The processing may be done by a single processor, or may be distributed over
different devices. The processing of signals referenced in this application can be
performed using the processor or over different devices. Processing may be done in
the digital domain, the analog domain, or combinations thereof. Processing may be
done using subband processing techniques. Processing may be done using frequency domain
or time domain approaches. Some processing may involve both frequency and time domain
aspects. For brevity, in some examples drawings may omit certain blocks that perform
frequency synthesis, frequency analysis, analog-to-digital conversion, digital-to-analog
conversion, amplification, buffering, and certain types of filtering and processing.
In various embodiments the processor is adapted to perform instructions stored in
one or more memories, which may or may not be explicitly shown. Various types of memory
may be used, including volatile and nonvolatile forms of memory. In various embodiments,
the processor or other processing devices execute instructions to perform a number
of signal processing tasks. Such embodiments may include analog components in communication
with the processor to perform signal processing tasks, such as sound reception by
a microphone, or playing of sound using a receiver (i.e., in applications where such
transducers are used). In various embodiments, different realizations of the block
diagrams, circuits, and processes set forth herein can be created by one of skill
in the art without departing from the scope of the present subject matter.
[0021] Various embodiments of the present subject matter support wireless communications
with a hearing assistance device. In various embodiments the wireless communications
can include standard or nonstandard communications. Some examples of standard wireless
communications include, but not limited to, Bluetooth™, low energy Bluetooth, IEEE
802.11(wireless LANs), 802.15 (WPANs), and 802.16 (WiMAX). Cellular communications
may include, but not limited to, CDMA, GSM, ZigBee, and ultra-wideband (UWB) technologies.
In various embodiments, the communications are radio frequency communications. In
various embodiments the communications are optical communications, such as infrared
communications. In various embodiments, the communications are inductive communications.
In various embodiments, the communications are ultrasound communications. Although
embodiments of the present system may be demonstrated as radio communication systems,
it is possible that other forms of wireless communications can be used. It is understood
that past and present standards can be used. It is also contemplated that future versions
of these standards and new future standards may be employed without departing from
the scope of the present subject matter.
[0022] The wireless communications support a connection from other devices. Such connections
include, but are not limited to, one or more mono or stereo connections or digital
connections having link protocols including, but not limited to 802.3 (Ethernet),
802.4, 802.5, USB, ATM, Fibre-channel, Firewire or 1394, InfiniBand, or a native streaming
interface. In various embodiments, such connections include all past and present link
protocols. It is also contemplated that future versions of these protocols and new
protocols may be employed without departing from the scope of the present subject
matter.
[0023] In various embodiments, the present subject matter is used in hearing assistance
devices that are configured to communicate with mobile phones. In such embodiments,
the hearing assistance device may be operable to perform one or more of the following:
answer incoming calls, hang up on calls, and/or provide two way telephone communications.
In various embodiments, the present subject matter is used in hearing assistance devices
configured to communicate with packet-based devices. In various embodiments, the present
subject matter includes hearing assistance devices configured to communicate with
streaming audio devices. In various embodiments, the present subject matter includes
hearing assistance devices configured to communicate with Wi-Fi devices. In various
embodiments, the present subject matter includes hearing assistance devices capable
of being controlled by remote control devices.
[0024] It is further understood that different hearing assistance devices may embody the
present subject matter without departing from the scope of the present disclosure.
The devices depicted in the figures are intended to demonstrate the subject matter,
but not necessarily in a limited, exhaustive, or exclusive sense. It is also understood
that the present subject matter can be used with a device designed for use in the
right ear or the left ear or both ears of the wearer.
[0025] The present subject matter may be employed in hearing assistance devices, such as
headsets, headphones, and similar hearing devices.
[0026] The present subject matter is demonstrated for hearing assistance devices, including
hearing aids, including but not limited to, behind-the-ear (BTE), in-the-ear (ITE),
in-the-canal (ITC), receiver-in-canal (RIC), or completely-in-the-canal (CIC) type
hearing aids. It is understood that behind-the-ear type hearing aids may include devices
that reside substantially behind the ear or over the ear. Such devices may include
hearing aids with receivers associated with the electronics portion of the behind-the-ear
device, or hearing aids of the type having receivers in the ear canal of the user,
including but not limited to receiver-in-canal (RIC) or receiver-in-the-ear (RITE)
designs. The present subject matter can also be used in hearing assistance devices
generally, such as cochlear implant type hearing devices and such as deep insertion
devices having a transducer, such as a receiver or microphone, whether custom fitted,
standard fitted, open fitted and/or occlusive fitted. It is understood that other
hearing assistance devices not expressly stated herein may be used in conjunction
with the present subject matter.
[0027] This application is intended to cover adaptations or variations of the present subject
matter. It is to be understood that the above description is intended to be illustrative,
and not restrictive. The scope of the present subject matter should be determined
with reference to the appended claims, along with the full scope of legal equivalents
to which such claims are entitled.
1. A hearing assistance device configured to be worn by a wearer, comprising:
a circuit configured to perform wireless communication;
an antenna coupled to the circuit, the antenna including:
two antenna elements; and
a cross-feed coupled to the two antenna elements to provide for electrical connection
between the two antenna elements, the cross-feed having a flared structure configured
to reduce capacitive coupling between the antenna and the wearer; and
a case housing the circuit and the antenna.
2. The hearing assistance device according to claim 1, wherein the two antenna elements
comprise two antenna loops, and the cross-feed comprises two cross-feed lines each
coupled between the two antenna loops.
3. The hearing assistance device according to claim 2, wherein the two antenna loops
are approximately symmetric and positioned in parallel.
4. The hearing assistance device according to any of claims 2 and 3, wherein the two
cross-feed lines each comprise a portion approximately perpendicular to each loop
of the two antenna loops.
5. The hearing assistance device according to any of claims 2 to 4, comprising two lines
each including a plurality of bends forming the flared structure, the two lines each
including a line of the two cross-feed lines.
6. The hearing assistance device according to claim 5, wherein the two lines each comprise
a line of the two cross-feed lines and portions of the two antenna loops.
7. The hearing assistance device according to any of claims 5 and 6, wherein the two
lines each comprise two approximately 45-degree bends forming the flared structure.
8. The hearing assistance device according to any of the preceding claims, comprising
a hearing aid including the circuit, the antenna, and the case.
9. The hearing assistance device according to claim 8, wherein the case is configured
to be worn behind the ear or over the ear.
10. A method for wireless communication to be performed by a hearing assistance device
configured to be worn by a wearer, comprising:
providing an antenna including two antenna elements and a cross-feed connected between
the two antenna elements; and
reducing capacitive coupling between the antenna and the wearer by configuring the
cross-feed into a flared structure.
11. The method according to claim 10, wherein providing the antenna comprises providing
two antenna loops and two cross-feed lines each connected between the two antenna
loops.
12. The method according to claim 11, further comprising configuring the two cross-feed
lines and portions of the two antenna loops into the flared structure.
13. The method according to any of claims 11 and 12, wherein configuring the cross-feed
into the flared structure comprises configuring each line of the two cross-feed lines
to include a plurality of bends.
14. The method according to claim 13, wherein configuring the cross-feed into the flared
structure comprises configuring each line of the two cross-feed lines to include two
approximately 45-degree bends.
15. The method according to any of claims 10 to 14, wherein reducing the capacitive coupling
between the antenna and the wearer comprises approximately reducing the capacitive
coupling between the cross-feed and the wearer.